When we say a thought is “about” something—that it has meaning, that it represents something in the world—we’re saying more than it just exists. We’re saying it has a function, a direction, a kind of fit between mind and world. But what grounds that fit?
What makes a mental state not only fire in the brain, but mean something? What keeps our thoughts from being arbitrary patterns of neural noise?
One powerful answer is found in teleo-semantics—a theory that explains mental content by appealing to purpose, function, and evolutionary history. It tells us that representation isn’t random, but naturalized through biology: through what our mental systems are for.
In this blog post, we’ll explore the core ideas of teleo-semantics, why it matters for understanding the mind, and how it transforms the old question of “what does it mean?” into “what was it selected to do?”
What Is Teleo-Semantics?
At its heart, teleo-semantics is an approach to naturalizing mental content. It was developed primarily by philosophers like Ruth Millikan and Fred Dretske, who aimed to explain meaning in biological, evolutionary, and functional terms.
“Teleo” comes from the Greek telos, meaning end or goal. In this theory, mental states represent what they do because of what they were designed (by nature or learning) to do.
Put simply:
A mental representation has the content it does because of the function it was selected to perform.
This isn’t about conscious intention. It’s about biological and cognitive functions—what mental states have been historically used to track, respond to, or coordinate with in the environment.
Key Idea: Content Through Proper Function
Teleo-semantics says that a mental state’s content depends on its proper function—that is, the role it was selected to play in a system that contributes to survival, learning, or cognition.
Example:
- A frog snaps at small, dark, moving objects. This behavior has evolved because it helps the frog catch flies.
- The internal state that triggers this behavior represents “fly,” not “small dark thing,” even though pebbles can also trigger it sometimes.
- Why? Because the function of that state, in the evolutionary history of frogs, was to track flies.
In this way, teleo-semantics distinguishes between correct representation (when the state tracks its proper target) and misrepresentation (when it doesn’t, but still performs its evolved function).
Why This Matters
1. Grounding Meaning in Nature
Teleo-semantics provides a naturalistic account of intentionality—one of the most mysterious features of mind. It avoids saying that meaning is something non-physical or magical. Instead, it shows how meaning can be a biological phenomenon, just like digestion or vision.
This makes mental content scientifically tractable: something we can study, not just describe.
2. Explaining Misrepresentation
If content were defined only by current causation (like in informational semantics), it would be hard to explain false beliefs. But with teleo-semantics:
- A belief can be about X even if X isn’t present now—because that belief has been selected or learned to track X.
- Misrepresentation is possible when a system functions as if it’s tracking its target, even when it gets it wrong.
This lets us explain how thought and language can go astray—something essential to understanding both cognition and communication.
3. Bridging Biology and Psychology
Teleo-semantics builds a bridge between mind and biology. It shows how psychological categories like belief and perception can be grounded in evolutionary function.
That’s especially important for fields like:
- Cognitive science: understanding how perception and decision-making evolved.
- Artificial intelligence: designing systems with representational states.
- Philosophy of mind: explaining mental phenomena without dualism.
Teleo-Semantics and Human Thought
Human minds are more than frog brains, of course. We don’t just track prey—we form abstract concepts, imagine futures, and tell stories.
How does teleo-semantics handle this?
- Learning and culture extend teleo-function beyond evolution. A belief might represent “justice” because it was taught to function in moral reasoning—even if it wasn’t selected by biology.
- The brain is a flexible architecture that supports representations shaped by both nature and nurture.
- Our language, tools, and social structures become part of the functional system that gives content its meaning.
In this way, teleo-semantics allows for a rich, layered picture of representation, one that respects our complexity without retreating into mysticism.
Some Challenges
No theory is without criticism. Common concerns include:
- Indeterminacy: What if a representation has multiple functions? Which one defines its content?
- Novel thoughts: Can teleo-semantics account for new or one-off concepts (like “unicorn” or “quantum entanglement”)?
- Normativity: Some argue that purpose alone can’t explain the normative force of belief—that beliefs aim at truth, not just function.
These are active areas of debate, but many philosophers are working on integrating inferential role semantics, social normativity, and pragmatic function into a fuller teleo-semantic picture.
Final Thoughts: The Purpose of Meaning
Teleo-semantics invites us to see mental content not as floating symbols or ghostly references, but as tools shaped by function—evolved and refined to help organisms survive, learn, and act intelligently.
It reframes the question of meaning from “What do I think this is about?” to “What was this thought for?”
It reminds us that cognition is not passive reflection, but active orientation—a dynamic process by which creatures engage a world that matters.
To understand meaning, in this view, is to understand purpose. And to understand purpose is to trace the story of how mind, body, and world have evolved together.
Because in the end, meaning is not just in what we say or believe.
It’s in what our minds are for—and how they help us find our way through the world.